Magnetic Fe3O4 nanorings for protein adsorption and detection

Iron oxide magnetic nanorings (Fe3O4 NRs) were successfully synthesized by hydrothermal route, and were developed as biosensor to adsorb and detect protein for the first time. The phase, microstructure, magnetic behavior, particle size of Fe3O4 NRs, and spin-spin relaxation time (T-2) change in detecting calreticulin (CRT) had been systematically investigated. X-ray Diffraction (XRD) and transmission electron microscopy (TEM) results showed that silane coated Fe3O4 NRs had a diameter about 100 nm, and almost distributed homogeneously. The modified Fe3O4 NRs had ferromagnetic behavior with saturation magnetization (Ms) as 62.4 emu g(-1). Furthermore, the Fe3O4 NRs detect for CRT limit was as low as 8 pg . mL(-1) in this work, which was much lower than traditional immunoblot analysis. This technique had great potential and high detection accuracy, and was more suitable for the detection of large quantities of clinical samples than the traditional immunoblot analysis.